The activities of this project currently comprise four main functions: 1) Identification of ticks received from various individuals and government agencies throughout the world. Only one other institution in the world is capable of performing this service. 2) Systematic study of certain groups of parasitic arthropods. The foremost tool in systematic studies, the scanning electron microscope, has greatly aided in elucidating toxonomic concepts in acarines actually or potentially involved in transmission of disease agents. 3) Final editing and storage of all RML and NAMRU-3 (Cairo) tick data in the Smithsonian data retrieval system. 4) Colonization of medically important arthropod vectors, which are furnished to outside investigators.